>>7447587

They're spots created when one body (like the Earth) orbits another body (Like the Sun). At the Earth-Sun Lagrange points, all the forces involved cancel out to create a point where an object can hang fixed relative to the Earth.

There are three forces involved - the gravity of Sun, the gravity of the Earth, and (because everything's spinning around on circular paths) centrifugal force.

At L1, the way they cancel out is pretty obvious - centrifugal force and Earth's gravity pull out, Sun pulls in, choose the distance where these cancel out.

L2 and L3 have all the gravity pointing in, so they pick a spot where going around at the same rate as Earth gives enough centrifugal force to cancel that out.

L4 and L5 are a little harder to explain. See, the Solar System doesn't orbit around the *center* of the Sun - the Earth also pulls back on the Sun, which causes it to wobble in a circular path as well. The Solar System actually orbits around the center of mass between the Earth and the Sun. At L4 and L5, because it's equal distances between the Earth and the Sun, their gravity cancels out into a net pull directly towards the center of mass. The satellite orbits around this point, causing it to keep pace with Earth.

These are the only points where gravity and centrifugal force cancels out like this.

Any two massive bodies orbiting each other have Lagrange points like this; there's Earth-Moon Lagrange points too, for instance.